1. Field of the Invention
This invention relates to a method for inhibiting corrosion of internal structural members of reinforced concrete structures, and more particularly, but not by way of limitation, to a method for inhibiting corrosion of the structural reinforcing member of reinforced concrete due to salt migration into the concrete.
2. Description of the Prior Art
It is well known that water repellancy has been provided buildings constructed of masonry cement by treating the surfaces of such buildings to render them repellant to liquid water. Many different compositions and methods have been proposed, including impregnating the surface of materials containing free hydroxyl groups, i.e., cement and lime, with organo silicon compounds having a hydrophobic effect in order to make the surface of the material water repellant and thus more resistant to the action of the weather. Further, it has heretofore been known that the application of such organo silicon compounds to a structure formed of a material containing free hydroxyl groups reduces the adherence of frozen water, ice, to the surface of the structure and thus the ice can be more readily removed.
Even with the advance of technology relating to the water repellancy of masonry cement buildings, problems have nevertheless remained relating to the deterioration of reinforced concrete structures, such as bridge decks and concrete paved roadways, due to deterioration of such reinforced concrete structures because of corrosion of the reinforcing steel members of the structure as a result of salt migration into the structure, or de-icer scaling of the surface of the structure subjected to wear.
The reinforcing steel corrosion problem is of greatest magnitude on bridge decks which are subject to frequent applications of deicing salt. The spalling resulting from the corrosion of the reinforcing members in the concrete structure affects the riding surface, thus forcing continual maintenance and eventually destroying the structural integrity of the deck. A similar problem exists in coastal areas when the bottom of bridge decks, beams, piling, and piers are exposed to saltwater or salt spray.
In an effort to retard or eliminate the corrosion of reinforcing steel in structural concrete, the most prevalent cause of deterioration of structural concrete, several different procedures have been proposed, namely, (a) methods to keep chlorides out of the concrete or at least to keep the chlorides from reaching the reinforcing steel, (b) coating the reinforcing steel itself so as to protect the steel from the influence of the chlorides, (c) methods to apply cathodic protection, (d) development of a noncorrosive deicer, and (e) other methods to neutralize the effect of chlorides.
Although the corrosion of the reinforcing steel in concrete has been recognized as the most prevalent cause of deterioration of structural concrete, and several possible methods have been proposed as a means to prevent or substantially reduce the corrosion of the reinforcing steel, problems have still remained, especially when attempting to solve the problems with water-repellant sealer compositions. The problem of using water-repellant sealer composition is that "Although some sealers have been found to reduce freeze-thaw scaling of non-air entrained concrete, none has been found which will eliminate significant chloride penetration into bridge deck riding surfaces subject to abrasive traffic wear for long periods of time." (FCP Annual Progress Report, Year Ending Sept. 30, 1978 under the project entitled "Eliminate Premature Deterioration of Portland Cement Concrete").